1. Field of the Invention
The present invention relates to a resonator utilizing a width expansion mode of a rectangular plate type vibrator, and more particularly, it relates to an energy-trap resonator having a structure which can effectively trap width expansion mode vibration.
2. Description of the Background Art
There have been developed piezoelectric resonators and piezoelectric filters which are used in various frequency ranges. However, substantially no effective piezoelectric resonator has been put into practice to be effectively used in the frequency range of 1 to 2 MHz, although a resonator utilizing a contour shear vibration mode of a rectangular plate type piezoelectric member has been commercialized to be used in this frequency range.
As described above, there has been no piezoelectric resonator which is effective in the frequency range of 1 to 2 MHz in general, while the commercially available piezoelectric resonator utilizing a contour shear vibration mode must be held with spring terminals, due to the properties of its vibration mode. Consequently, the structure for holding the piezoelectric resonator is inevitably increased in size.